Trigger mechanisms for recoiling automatic guns of the open breech type



Sept. 22, 1959 B MAILLARD 2,905,058

TRIGGER MECHANISMS FOR RECOILING AUTOMATIC GUNS OF THE OPEN BREECH TYPE Filed May 16, 1955 2 Sheets-Sheet 1 INVENTDR ATTUPINEY Sept. 22, 1959 MAlLLARD 2,905,058

TRIGGER MECHANISMS FOR RECOILING AUTOMATIC GUNS OF THE OPEN BREECH TYPE Filed May 16, 1955 2 Sheets-Sheet 2 INVENTDR BETA FFDflF/LMIPO,

AT TDHNEKS Z,%5,tl58 Patented Sept. 22, 1959 TRIGGER MECHANISMS FOR RECOILING AUTO- MATIC GUNS F Tim OPEN BREEQH TYPE Bernard Mailiard, Geneva, Switzerland, assignor to Brevets Aero-Mecaniques S.A., Geneva, Switzerland, a Swiss society Application May 16, 1955, Serial No. 508,646

Claims priority, application Luxemburg, May 21, 1954 1 Claim. (Cl. 89---150) The present invention relates to trigger mechanisms for recoiling automatic guns of the open breech type, the term recoiling automatic gun meaning that the arm proper is mounted movable on a fixed support (cradle) with respect to which it recoils, every time a shot is fired, against the action of a damping system, said gun firing continuously until the pressure on the trigger is released. The term of the open breech type designates all automatic guns including a breech-block having a reciprocating movement and which is held in rear position when the arm is not firing by means of a trigger mechanism so that when firing is to be resumed, said breech-block Starts from said rear position so as to catch a fresh cartridge and to bring it into the cartridge chamber of the gun.

The object of the present invention is to provide a trigger mechanism which is better adapted to meet the requirements of practice than those used at the present time.

Such a mechanism includes a locking device adapted, when in operative position, to keep the nose of the sear member out of the path followed by a holding abutment carried by the breech-block of the gun. The present invention consists in mounting this locking device on the gun support and in controlling it in such manner, by means ofa part which participates in the recoil movement of the gun with respect to its support, that said lockingdevice remains in operative position (and therefore makes it impossible to stop firing) at least during the portions of the cycle of operation of the breech-block where release of the sear member would cause an incomplete engagement of said breech-block by said sear memher, said locking device being on the contrary moved away from its operative position by said part (whereby it is then possible to stop firing) during at least one of the portions of the cycle of operation of the breech-block where release of the sear member will subsequently produce a suitable engagement of said breech-block with said sear member.

Preferred embodiments of the present invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

Fig. 1 is a diagram illustrating the cycles of operation of the breech-block and of the gun proper, this diagram serving to illustrate the principle of the present invention.

Fig. 2 is a diagrammatical view of a trigger mechanism for an automatic gun according to the present invention.

Figs. 3 and 4 are views similar to Fig. 2 but showing two diiierent positions of the parts.

The automatic gun shown by the drawings includes a..breech-b1ock 1 slidable in a breech casing 2 which is itself movable, under the effect of recoil and against the action of a damping resilient system (not shown), with respect to a fixed cradle 3 acting as support for the gun proper. During their recoil movements, said breechblock 1 and said breech casing 2 move toward the right hand side of Figs. 2, 3 and 4.

The trigger mechanism includes in known fashion a sear 4 pivoted about an axis 5 fixed with respect to breech casing 2, this sear having a nose 6 capable of coming, under the action of'a spring 7, across the path followed by an abutment constituted by the end 8 of a notch provided in breech-block 1. When the nose 6 of sear 4 is applied against abutment 8, breech-block 1 is in open position.

Control means are interposed between the trigger proper (not shown), which is operated by the gunner, and sear 4. This mechanism is arranged in such fashion that, when the gunner pulls the trigger, the nose 6 of the sear is retracted, that is to say moves against the action of return spring 7 away from the path followed by abutment 8 during the reciprocating movement of breech-block 1.

In the embodiment illustrated by the drawings, the trigger system includes a rod 9 controlled by the trigger proper and connected to a lever including two arms 10 and 11 pivoted about an axis 12 fixed with respect to the gun cradle 3, rod 9 being pivoted to one of the ends of lever arm 10.

The other arm 11 of the lever cooperates with a lever 13 having also two arms and pivoted on the breech casing 2 about an axis 14. One of the arms of said lever 13 carries a roller 15 which bears upon a ramp 16 provided on lever arm 11. The other arm of lever 13 carries a finger 17 engaging a groove 18 provided in sear 4. When lever 13 is pivoted in a clockwise direction, the nose 6 of the sear is moved away from the abutment 8 of breech-block 1.

Lever arm 11 is bent at an angle such that, when the gun is firing (i.e. when rod 9 is being pulled in the direction illustrated by arrow F on Fig. 2), ramp 16 is parallel to the recoil movement of the gun, whereby roller 15 can run on said ramp every time the gun recoils, without modifying the angular position of lever 13, that is to say without influencing the retracted position of sear 4.

With such an arrangement taken alone, the gunner might release sear 4 at any time during the cycle of operation of the gun, and in particular at a time when the nose 6 of the sear would no longer have time, under the action of return spring 7, to engage sufficiently deep in the notch of breech-block 1 to engage suitably with the abutment 8 at the end of said notch. This would result in injuring nose 6 and abutment 8.

Fig. 1 illustrates the operation of the sear.

This figure shows a curve A in dotted lines showing in ordinates the position of the gun proper, that is to say of breech casing 2 with respect to fixed support 3, the time being plotted in abscissas.

A curve B in solid lines similarly shows the reciprocating movement of breech-block 1.

In this figure, the upward portion of the curves represent recoil displacements and the downward portions counter-recoil displacements. The battery position of the parts is on line ed and the gun fires at each of said successive points e-d,

On curve B, 11 indicates the point corresponding to time I; where the breech-block in open position has its abutment 8 engaged by the nose 6 of the sear, thus 3 stopping firing. b indicates the point corresponding to time t where, during the recoil movement of the breechblock, abutment 8 passes opposite the nose 6 of sear 4.

m indicates the last possible point (corresponding to time t where the nose 6 of scar 4, supposed to have been released and to be moving upwardly under the action of spring '7, must have reached the level of the lower end of abutment. 8 so as to be sure that said sear engages in a satisfactory fashion into the notch, at the latest at time It will be understood that if the sear is released so that its nose 6 reaches the level of the lower end of abutment 8 after time t an unsatisfactory engagement of said sear with abutment 8 at time t will take place. Of course time I is between time t and t It should be well understood that satisfactory engagement of the sear nose 6 into the breech-block notch does not mean that said nose is fully engaged, but is sufficiently engaged therein.

Fig. 1 therefore shows that sear 4 should not be allowed to move toward the path of travel of abutment 8 during a period such that its nose 6 will reach the level of the lower end of abutment 8 at a time ranging between 1 and t Of course, the period for which the sear should not be thus released starts before time t and ends before time t since upward movement of the sear under the effect of its spring requires some time between the release of the scar and the instant when it comes at the level of the lower end of abutment 8.

It has already been proposed, in order to prevent unsatisfactory engagement of the sear with the breech-block, to provide the breech casing 2 with a safety device arranged in such manner as to lock sear 4 in retracted position for the suitable period of the cycle of operation.

Such an arrangement involves serious drawbacks. In particular it complicates the gun construction and increases the weight thereof.

Furthermore the fatigues of the parts of the safety device are considerable due to the accelerations inherent in the operation of the gun proper (in particular recoil movement).

The object of the present invention is to eliminate these drawbacks.

For this purpose and according to the present invention, the means for locking the sear in retracted position are carried by the support 3 of the gun and said locking means are controlled by a part which participates in the recoil movement of the gun proper, i.e. of the breech casing, in such manner that said locking device remains in active position at least during the period for which the sear is not be released and is moved away from said active position during a period outside of the above mentioned period.

Preferably, in order to obtain a large margin of safety, the locking device is controlled in such manner that it is held in active position for a period much larger than that theoretically necessary.

For instance, the release of the sear is made possible only during the end of the return of the gun into firing position and during the beginning of its recoil stroke, the first of these periods being limited by points c and d on curve A whereas the other period is limited by points 2 and 1.

Thus the sear can be relased only at a point such as indicated at n between and d or n between e and f.

If the sear is released at the end of the return of the gun into firing position, one more shot will be fired when the breech-block 1 arrives to point e and said breechbl'ock will be hooked and fixed in position only during the next recoil stroke, at time 11, when the abutment 8 comes opposite the nose 601. the sear.

On the contrary, if the sear is released at the beginning of the'recoil stroke of the gun i.e. between 2 and f), breech-block 1 will be fixed at, the next time t i.e. when,

during the recoil stroke, abutment 8 comes opposite."

the nose 6 of the scar and no shot will be fired after the trigger is pulled.

In the specific embodiment of the invention illustrated by the drawings, a fork-shaped lever 20 is pivoted about an axis 19 on the support 3 of the gun. Each of the branches of said lever 20 carries a shoulder 21 capable, when lever 20 has been brought into vertical position by return spring 22, of cooperating with a heel 23 rigid with lever arm 11, lever 11 being in firing position, that is to say in the position for which ramp I6 is parallel to the recoil movement of the gun.

Breech casing 2 carries an abutment 24 positioned in such manner that it keeps lever 20 away from vertical position during the end of the counter stroke of the gun (portions 0, d of the curve) and at the beginning of its recoil stroke (portions 2, f of the curve).

Thus, during the period corresponding to these two.

zones, shoulders 21 are at a distance from heels 23 and control lever 1011 can be actuated by the trigger rod 9.

Fig. 2 shows the elements of the trigger mechanism in the respective positions they occupy when, the gun firing a burst, the locus illustrating the movement of the breech-casing lies between points 1 and c. The sear 4 is then retracted and the trigger mechanism is prevented from operating by locking lever 20.

Fig. 3 shows the parts of the trigger mechanism in the respective positions they occupy when, the gun firing a burst, the locus illustrating the movement of the breechcasing lies between points 0 and d or between points 2 and 1, that is to say in portions of the stroke such that sear 4 can be released by operating trigger rod 9. Locking lever 20 is then moved away from its active position by abutment 24. V

In Fig. 4, the parts are in relative positions such that the trigger rod 9 has been actuated so as to stopfiring and sear 4- has come into active position.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claim.

What I claim is:

An open-breech recoil operated automatic gun which comprises, in combination, the support for said gun, a breech-casing reciprocable longitudinally on said support, a breech-blocking reciprocable longitudinally in said breech casing, a sear pivotally mounted on said breech casing, said. breech-block having a sear notch so disposed as to cooperate with said sear, said sear being adapted to occupy a retracted position with respect to said breechbloek and an active position with respect to the reciprocal path of said abutment, a first lever arrangement pivoted to said support about an axis at right angles to the direction of movement of said breech-block, a trigger rod hinged to the end of one arm of said first lever arrangement, the other arm of said first lever arrangement being bent so as to form a ramp parallel to the line of fire. of said gun for a given position of said first lever arrangement, a second lever arrangement pivoted to said breech-casing about an axis transverse to the movement of said breech-block, a bearing member carried by the end of one arm of said second lever arrangement and cooperating. with said ramp by moving thereon, said sear being provident with a groove passing substantially through its pivot axis, a finger carried by the end of the other arm .of said second lever arrangement and engaging said groove for controlling the movement of said sear, resilient means for urging said sear toward active position,."a-locking lever carried by said support and including a shoulder adapted, to cooperate with the second mentioned arm. of said first lever arrangement for holding it in" its position where said ramp is parallel to the line 5 6 of fire of the gun, resilient means for urging said locking References Cited in the file of this patent lever toward said position, and an abutment rigid with UNITED STATES PATENTS said breech casing for acting on the end of sald locking lever to bring it out of locking position against the action 9751286 Ross 1910 of said resilient means, said abutment rigid with said 5 2,088,877 Stange 7 1937 breech casing being positioned to bring said locking lever 23971387 Trevaskls 1946 into inoperative position only for portions of the stroke of said breech-block where movement of said sear toward FOREIGN PATENTS active position by said second lever arrangement can 616,617 Great Britain 9 achieve a satisfactory engagement of said sear with said 10 sear notch provided in said breech block. 

